curl --request GET \
  --url https://api.hubapi.com/automation/v4/actions/{appId}/{definitionId}

{
  "functions": [
    {
      "functionType": "PRE_ACTION_EXECUTION",
      "id": "<string>"
    }
  ],
  "actionUrl": "<string>",
  "published": true,
  "labels": {},
  "inputFields": [
    {
      "isRequired": true,
      "automationFieldType": "<string>",
      "typeDefinition": {
        "helpText": "<string>",
        "referencedObjectType": "CONTACT",
        "name": "<string>",
        "options": [
          {
            "hidden": true,
            "displayOrder": 123,
            "doubleData": 123,
            "description": "<string>",
            "readOnly": true,
            "label": "<string>",
            "value": "<string>"
          }
        ],
        "description": "<string>",
        "externalOptionsReferenceType": "<string>",
        "label": "<string>",
        "type": "string",
        "fieldType": "booleancheckbox",
        "optionsUrl": "<string>",
        "externalOptions": true
      },
      "supportedValueTypes": [
        "STATIC_VALUE"
      ]
    }
  ],
  "outputFields": [
    {
      "typeDefinition": {
        "helpText": "<string>",
        "referencedObjectType": "CONTACT",
        "name": "<string>",
        "options": [
          {
            "hidden": true,
            "displayOrder": 123,
            "doubleData": 123,
            "description": "<string>",
            "readOnly": true,
            "label": "<string>",
            "value": "<string>"
          }
        ],
        "description": "<string>",
        "externalOptionsReferenceType": "<string>",
        "label": "<string>",
        "type": "string",
        "fieldType": "booleancheckbox",
        "optionsUrl": "<string>",
        "externalOptions": true
      }
    }
  ],
  "revisionId": "<string>",
  "archivedAt": 123,
  "inputFieldDependencies": [
    {
      "dependencyType": "SINGLE_FIELD",
      "controllingFieldName": "<string>",
      "dependentFieldNames": [
        "<string>"
      ]
    }
  ],
  "executionRules": [
    {
      "labelName": "<string>",
      "conditions": {}
    }
  ],
  "id": "<string>",
  "objectTypes": [
    "<string>"
  ],
  "objectRequestOptions": {
    "properties": [
      "<string>"
    ]
  }
}